heart anatomy

Pericardium

* double-layered connective tissue sac
* holds heart in place.

Serous pericardium

* Parietal layer
* visceral layer

Fibrous pericardium

* Superficial layer
* anchors heart in place

pericardial cavity

* potential space inside pericardial layer
* pericardial fluid: cushions heart, provides lubrication.

epicardium

* outer most layer of the heart
* visceral pericardium

Myocardium

* Middle layer of the heart
* cardiac muscle

endocardium

deepest tissue of the heart

endothelial muscle

L and R atria

* Receive blood from great veins.
* separated by interatrial septum.
* R atrium: Pectinate muscles

L and R Ventricles

* send out blood into great ventricles.
* Separated by interventricular septum.
* Trabeculae carneae

Heart in cross section

* L ventricles more muscular
* IV septum bulges into R ventricle
* L ventricle circular shaped
* R ventricle C- shaped

Valves

* ensure one- way flow.
* snap shut against back flow.

Atrioventricular valves

Mitral

tricuspid

semilunar valves

aortic

pulmonary

Tricuspid

* Between right atrium and ventricle
* 3 cusps

Mitral

between L atrium and ventricle

2 cusps

Papillary muscles

projection of muscles from floor of ventricles.

chorda tendineae

collagen fibers attaching papillary muscles to AV valves.

Papillary Muscles and \n Chordae Tendineae

* Contract during ventricular contraction: hold AV valves shut. \n
* Prevent backflow into atria.

semilunar valve’s function

* Regulate blood flow from ventricles into great arteries: pulmonary and aortic.
* 3 cusps shaped cusps.
* catch backflow of arterial blood when ventricles relax.

cardiomyocytes

* High energy which requires many mitochondria
* Separated by the intercalated discs.
* Interdigitating folds- interlock cells

Intercalated discs

* Gap junctions: allow electrical impulse to travel between cells.
* Fascia adheres and desmosomes- prevent contracting cells from pulling apart.

Myocardial vortex

* Spiral arrangements of cardiomyocytes
* enhances blood flow during contractions.

Fibrous skeleton

Framework of structures between heart chamber and around great blood vessels

functions:

Anchors cardiomyocytes

Provides electrical insulation.

provide structural support.

R side-→ pulmonary circuit

* Receives blood from superior and inferior venae cava.
* Oxygen poor blood to lungs via pulmonary trunk

L side --→ systemic circuit

* Receives blood via the pulmonary veins.
* Oxygenated blood to all tissue of the body via the aorta.

Superior and inferior vena cava

venous blood returned to R atrium.

pulmonary trunk and arteries

Low oxygen blood to lungs

Pulmonary veins

Return high oxygen blood to L atrium.

Aorta

Supply high oxygen blood to body.

coronary arteries

* Heart has high energetic need:

receives -5% of circulating blood flow.

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* R and left Coronary arteries:

From aorta immediately superior to L ventricle

Supplied by back flow.

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Left Coronary Artery (LCA)

* Travels through coronary \n sulcus
* Anterior interventricular \n branch \n • AKA Left Anterior \n Descending artery \n • Supplies both ventricles, \n anterior 2/3 of IV septum
* Circumflex branch \n • Supplies left atrium and \n posterior wall of left \n ventricle \n

Right Coronary \n Artery (LCA)

* Supplies right atrium and \n sinoatrial node \n
* Right marginal branch: \n Supplies lateral portions of \n right atrium and ventricle
* Posterior \n interventricular branch \n • Supplies posterior walls \n of both ventricles and \n posterior 1/3 of \n interventricular septum

Venous Return

* Great cardiac vein drains \n anterior portion of heart \n
* Middle/posterior cardiac veins \n drain posterior heart. \n
* Empty into coronary sinus, \n which empties into right atrium